*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
.cover{
    width:400px;
    height: 300px;
    margin: 150px auto;
    position: relative;
    border: 1px solid #666;
    overflow: hidden;
}
ul{
    position: absolute;
    top: 150px;
    width: 400px;
    transition: top 1s linear;
}

ul>li{
    list-style: none;
    height: 30px;
    line-height: 30px;
    text-align: center;
    width: 400px;
}

.active{
    color: #269;
}